The invention relates to a pipe with an external sealing body.
These known pipes are used in bore holes of coal stratums in mining industries for sucking off gases. In coal stratums presenting a high methane concentration, the methane should be sucked off in order to decrease the risks of explosion.
So as to obtain a reliable suction a pipe is pushed into each bore hole, while moreover the hollow space between the bore hole wall and the pipe is sealed. The pipes in the bores are connected with a mutual gas pipe line which in its turn is connected with a blower, providing the sub-atmospheric pressure required for removing the gases by suction.
The above mentioned sub-atmospheric pressure, however, not only improves a suction action with respect to methane gases, but also causes a reduced methane concentration in the gas mixture to be removed if air leaks toward the suction opening and thus a reduction of methane in the mixture removed by suction.
An efficient sealing should therefore be carried out, in order to avoid a suction action of the gas mixture from the mine proper and not from the coal stratums with methane concentrations.
Up to now a foam rubber body has been glued on known pipes, whereafter the body is covered with a resilient paste, acting as a sealing means, which structure is then covered with a resilient expandable wear resistant cover for obtaining a sealing body having a diameter which always exceeds the one of the bore hole in which the pipe is accommodated.
Such a sealing body has the drawback that it can only be provided with much work expenditure, whereas shifting of the same can also occur when a pipe is used with an insufficient glue connection between sealing body and pipe.